Generally, a wire guide can be used for the placement of a catheter into a vascular system. A wire guide has a proximal end that is held by a physician and a distal end that is inserted into the vascular system. A physician may insert a needle with the wire guide into an artery, vein or other vessel. The wire guide is introduced through the needle into the vessel. Next, the needle is withdrawn over the wire guide, then a catheter or another medical device is placed over the wire. This medical device and the wire guide are maneuvered together to a part of the vascular anatomy at which the physician is performing an interventional or diagnostic procedure.
These wire guides include low coefficient of friction coatings so the catheters can be advanced over them freely and they can be passed into the vascular anatomy easily. These coatings are typically made of Polytetraflouroethylene (Teflon), and hydrophilics (polyvinylpirilidone). The Teflon coating is usually effective for allowing free movement of the catheter over the wire guide, but not effective for allowing the wire guide to pass freely into the vascular anatomy. The hydrophilic coating is effective for allowing the wire guide to advance into the vascular anatomy and allowing free movement of the catheter over the wire, however, the hydrophilic coating is too slippery to allow the physician to grip and maneuver the wire guide.
One of the problems with such wire guides is that they do not provide a good feel for the physician, which makes it difficult to determine if the wire guide is advancing through the vascular anatomy or if the physician's fingers are slipping along the proximal end. Some methods or devices have attempted to provide the appropriate feel and control of the wire guides. One device is a pin vise type that securely clamps to the proximal end of the wire. This device is described in U.S. Pat. No. 5,325,746. This device acts as a handle for the wire guide, which allows a physician to easily manipulate the wire guide. Since this device usually must be positioned and repositioned during an invasive procedure, a physician using it may find it difficult and/or cumbersome to operate. Another attempted solution involves coating the distal end of the wire guide with a hydrophilic layer leaving the proximal end uncoated to prevent the proximal end from being slippery. This approach allows the physician to feel and manipulate the wire guide in the usual manner. Since the proximal end is uncoated, however, it can stick or bind in the lumen of the catheter or super-selective catheter. A super-selective catheter is a specially made medical device used to enter vessels that are inaccessible by normal catheters. More specifically, the proximal end of the wire guide can bind to the lumen of superselective catheters made of Nylon, making it difficult to use the wire guide with the catheter. Therefore, there is a need for an apparatus and a method that enables a user to retain a good grip on the wire guide while providing enough lubricity to allow the wire guide to function well.